GB2033352A

GB2033352A - Gripper heads forcontainer closing machines

Info

Publication number: GB2033352A
Application number: GB7936330A
Authority: GB
Original assignee: Rationator Maschinenbau GmbH
Current assignee: Rationator Maschinenbau GmbH
Priority date: 1978-10-27
Filing date: 1979-10-19
Publication date: 1980-05-21
Also published as: US4309859A; SE7908772L; SE438143B; NL7907547A; FR2439744A1; CH641124A5; DE2846846A1; FR2439744B1; NL189458B; GB2033352B; IT1126153B; IT7983477A0; NL189458C; DE2846846C2

Description

1 GB 2 033 352 A 1

SPECIFICATION Gripper heads for closing machines

The invention relates to gripper heads for closing machines for example machines for applying screw closures to receptacles, of the kind 70 having an open-ended sleeve for receiving the closure, and an element therein for gripping the inserted closure.

In a known gripper head of this kind, used in a filling and closing machine, the closure is placed 75 on the receptacle and screwed up with a predetermined torque. In this known form of construction the head is suited to the form and - size of the closure, a shaped rubber piece or spring catch or the like being inserted into the interior.

This has the, disadvantage that a special head has to be provided for each shape of closure and this, in view of the many shapes and sizes of such receptacles, means an enormous expense. The closures, which mostly are of plastics material, vary in dimensions to take care of permissible manufacturing tolerances, so that it can happen that individual closure caps are inadequately held in the head or that the necessary screwing up torque cannot be applied. In addition there is the drawback that in the case of delicate closures there may be damage caused by friction. This is particularly the case when, because of inadequate retention in the head the headstock rotating at high speed may tear the closure.

Also known is a gripper head of this nature in which a rubber ring is axially gripped in the sleeve and is axially compressed outwards from the spindle by a piston, so that it will bulge out radially. This construction is likewise attended by notable drawbacks. The rubber ring must be very elastic to keep the pressure pistons of reasonable dimensions. This however also meaw; particularly severe friction, meaning that the retaining element 4() has to be frequently replaced. The pressure piston guided in the headstock has to be appropriately sealed against the pressure fluid, A comparatively high pressure is required to produce the axial pressure needed to bring about the required radial expansion of the rubber element, with the result that the sealing is heavily stressed and becomes ineffective, it breaks down and the pressure fluid escapes. Because of this comparatively high pressure the venting period is comparatively long and a lot of noise is produced. There is also the danger that the closures will not remain accurately centred in the head.

It is an object of the pfesent invention to construct a gripper head of this nature in such a way that the closures are accurately centred and 120 held against slip and against damage and can be screwed up on the receptacle independently of variation in size arising from size tolerances.

This object is met in accordance with the present invention by the fact that a flexible diaphragm is arranged in the sleeve as gripper element and can be radially compressed by a pressure fluid.

In an advantageous construction, spacer ribs defining ducts for the passage of pressure fluid to the diaphragm are provided between the diaphragm and the closed end of the sleeve and the side wall of the latter.

A useful arrangement moreover is that in which a fastening cap is disposed over the open end of said sleeve and clamping a marginal part of said diaphragm in U-shape and in sealing fashion against an end edge of said sleeve.

By another feature of the invention a rubber ring is disposed within said diaphragm for engagement with the receptacle.

A further advantage lies in an arrangement in which gripperjaws are disposed within said sleeve and within said diaphragm and movable by the latter to grip and release the closure.

It is here of advantage to arrange compression springs between the gripper jaws and these jaws may have outstanding marginal rims.

The head of this invention has the outstanding advantage that the closure is received accurately_ centred in it and can readily be placed on the receptacle and screwed up thereon with the necessary torque. The closures are held securely until reaching the set torque, damage being eliminated. Large size tolerances of the closures are eliminated, so that a simple adaption to different sizes of closure can be affected, for example by replacement of the rubber ring arranged in the interior thereof where this is provided. A further and substantial advantage resides in the fact that simple sealing is possible, because the diaphragm itself represents the sealing element. Here low pressures can be used. The gripper head according to the invention is further typified by a particularly simple construction.

In the embodiment with the gripper jaws there is an additional advantage in that the closures can be used on the receptacles when the latter are packed close to one another or only a limited spacing is available between the vessels in the vicinity of the closure. This embodiment gives independence from the contents of the containers because the jaws can be made of a material which is resistant to the container content. Where the closures are of complicated external shape the jaws can be inserted as moulded elements in the gripper head.

Embodiments of the invention are illustrated in the accompanying drawings, in which:

Figure 1 is a longitudinal section through a first embodiment of a gripper head of this invention, Figure 2 is a longitudinal section through a second embodiment of the head, Figure 3 is a cross section on the line A-A of Figure 1, and Figure 4 is a section on the line B-B of Figure 2.

In the embodiment illustrated in Figures 1 and 3 the gripper head 1 has an upstanding spigot with an internal thread 2 by means of which it is screwed on to the closing machine proper. The lower part of the head forms a sleeve 3 which, in the embodiment illustrated, is cylindrical. A receptacle closure 5, shown in dot and dash lines in the drawing, is received in the hollow chamber 2 GB 2 033 352 A 2 4 defined by the sleeve 3.

The sleeve 3 is provided with spaced ribs 9 45 which upstand from the bottom of chamber 4 and spaced longitudinal ribs 10 projecting inwards from the lateral wall defining this chamber. The sleeve is further provided with internal passages to permit the supply of pressure fluid to the ducts 12 defined between the various ribs 9 and 10.

A diaphragm 6 is disposed within the open end of sleeve 3 and is fastened to the latter by means of a washer 13 which covers the complete bottom face of the diaphragm. The diaphragm is wrapped in U-section around the bottom edge 14 of the sleeve 3 and is held and sealed by a screw cap 15 screwed up on the sleeve. Disposed in the chamber 4 within the diaphragm and bearing against the latter is a rubber ring 16 held by the screw cap 15.

To grip a closure 5, pressure medium is driven through the ducts 12 into the lateral medium is driven through the ducts 12 into the lateral spaces between the ribs 10. This correctly centres the diaphragm and the ring 16 is pressurised inwards towards the axis 7 thereby to hold the closure 5 firm. The ring 16 is pressed inwardly uniformly over its complete depth so that the full depth of ring is used to grip. The closure 5 is released by venting through ducts 12.

Figures 2 and 4 show a further embodiment of a gripper head of this invention, the same numerals being used as for the comparable parts in the embodiment illustrated in Figures 1 and 3.

In this second embodiment gripper jaws 17 are arranged in the chamber 4 and are held against the sleeve 3 by an annular part 19, which also grips the diaphragm 6. The annular part 19 is of form in cross section. The individual jaws 17 are guided for radial displacement about the central constriction 21 of part 19 and pushed together by the pressurising of the diaphragm 6. These jaws 17 together define an outwardly facing gripping opening 18 defined by thin depending parts 22 of the jaws.

Figure 4 indicates in more detail compression springs 20 arranged between the individual jaws 17 to push them in the opening direction. These compression springs can be dispensed with if the spindle is operated at high speed and the jaws are forced outwards by the induced centrifugal force.

Claims

1. In or for a closing or capping machine, for example for applying screw closures to receptacles, a gripper head for holding a closure and comprising an open-ended sleeve to receive the closuire, a flexible diaphragm disposed within said sleeve, and means for applying fluid pressure to said diaphragm to contract the same around a closure disposed in the said sleeve.

2. A gripper head according to Claim 1 in which spacer ribs defining ducts for the passage of pressure fluid to the diaphragm are provided between the diaphragm and the closed end of the sleeve and the side wall of the latter.

3. A gripper head according to Claim 1 or 2, further comprising a fastening cap disposed over the open end of said sleeve and clamping a marginal part of said diaphragm in U-shape and in sealing fashion against an end edge of said sleeve

4. A gripper head according to any of Claims 1 to 3, in which a rubber ring is disposed within said diaphragm for engagement with the receptacle.

5. A gripper according to any of Claims 1 to 3, further comprising gripper jaws disposed within said sleeve and within said diaphragm and movable by the latter to grip and release the closure.

6. A gripper head according to Claim 5, in which compression springs are arranged between the gripper jaws. 80

7. A gripper head according to Claim 5 or 6, in which the gripper jaws have outstanding marginal rims.

8. In or for rece pta cl e-c losing machines gripper heads substantially as herein described and shown in the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1980. Published by the Patent Office. 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.

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